Use of OmpU porins for attachment and invasion of Crassostrea gigas immune cells by the oyster pathogen Vibrio splendidus

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 108; no. 7; pp. 2993 - 2998
• Main Authors: Duperthuy, Marylise, Schmitt, Paulina, Garzón, Edwin, Caro, Audrey, Rosa, Rafael D, Le Roux, Frédérique, Lautrédou-Audouy, Nicole, Got, Patrice, Romestand, Bernard, de Lorgeril, Julien, Kieffer-Jaquinod, Sylvie, Bachère, Evelyne, Destoumieux-Garzón, Delphine
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.02.2011; National Acad Sciences
• Subjects: Actins; Adhesins, Bacterial - metabolism; Analysis of Variance; Animals; Bacteria; Bioengineering; Biological Sciences; Blood plasma; Cells; Cholera; Chromatography, Liquid; Crassostrea - immunology; Crassostrea - microbiology; Crassostrea gigas; Ecology, environment; Electrophoresis, Polyacrylamide Gel; Environmental studies; Flow Cytometry; France; Green Fluorescent Proteins - metabolism; Hemocytes; Hemocytes - microbiology; Hemolymph; Host-Pathogen Interactions; Humanities and Social Sciences; Imaging; Immune system; Immunity, Innate - immunology; Life Sciences; Microscopy, Confocal; Oxygen; Oysters; Parasite hosts; Pathogens; Phagocytosis; Plasma; Polymerase Chain Reaction; Porins - metabolism; Statistics, Nonparametric; Superoxide Dismutase - metabolism; Tandem Mass Spectrometry; Vibrio; Vibrio - metabolism; Vibrio - pathogenicity; Vibrio splendidus; France
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1015326108

OmpU porins are increasingly recognized as key determinants of pathogenic host Vibrio interactions. Although mechanisms remain incompletely understood, various species, including the human pathogen Vibrio cholera, require OmpU for host colonization and virulence. We have shown previously that OmpU is essential for virulence in the oyster pathogen Vibrio splendidus LGP32. Here, we showed that V. splendidus LGP32 invades the oyster immune cells, the hemocytes, through subversion of host-cell actin cytoskeleton. In this process, OmpU serves as an adhesin/invasin required for β-integrin recognition and host cell invasion. Furthermore, the major protein of oyster plasma, the extracellular superoxide dismutase Cg-EcSOD, is used as an opsonin mediating the OmpU-promoted phagocytosis through its RGD sequence. Finally, the endocytosed bacteria were found to survive intracellularly, evading the host defense by preventing acidic vacuole formation and limiting reactive oxygen species production. We conclude that (i) V. splendidus is a facultative intracellular pathogen that manipulates host defense mechanisms to enter and survive in host immune cells, and (ii) that OmpU is a major determinant of host cell invasion in Vibrio species, used by V. splendidus LGP32 to attach and invade oyster hemocytes through opsonisation by the oyster plasma Cg-EcSOD.